The injury of marginal mandibular branch unexpectedly promotes the repair of buccal branch of facial nerve in a rat model

Abstract

Conclusions: The results indicate that the injury of the marginal mandibular branch improved the recovery of the buccal branch in a rat model.Objective: The aim of this study was to investigate whether the injury or intactness of the marginal mandibular branch affects the regeneration of the facial nerve buccal branch in a rat model.Methods: This experiment was conducted on 30 adult rats, which were randomly and equally divided into two groups. The buccal branch of the facial nerve was transected and reconstructed, with the marginal mandibular branch damaged (group A) or intact (group B). The vibrissae movement of rats was assessed since the 4th week after operation. At the 8th and 12th week, compound muscle action potentials (CMAPs) and morphological changes of injured buccal branches were evaluated.Results: After the operation, vibrissae movement of rats was eliminated in group A, but it was similar to the health side in group B. CMAPs were recorded from regenerated buccal branches in group A since the 8th week, but no CMAPs could be recorded in group B at each time point. Additionally, the diameter of nerve fibers, the thickness of myelin sheath, and the density of regenerated fibers in group A were significantly larger than those in group B (p < 0.05).